1. Field of the Invention
This invention relates to an exercise apparatus, more particularly to an exercise apparatus with an adjustable resistance assembly.
2. Description of the Related Art
FIG. 7 illustrates a prior stationary bicycle 80. The stationary bicycle 80 comprises a frame 81, a seat 82, a pedal mechanism 83 and a rotating member 84. A user can sit on the seat 82 and drive the pedal mechanism 83 to rotate the rotating member 84 for exercising with basic intensity. Besides, the user can operate an adjustable resistance assembly 90 which is configured on the frame 81 over the rotating member 84 to increase or decrease friction resistance which is exerted on the rotating member 84. The adjustable resistance assembly 90 can also be operated to immediately exert large friction resistance on the rotating member 84 to stop the rotating member 84 at short time.
Pleases refer to FIG. 8, the adjustable resistance assembly 90 comprises a guiding tube 86 approximately vertically mounted on the frame 81. From top to bottom, there are a screw rod 91, a medium spring 92 and a pushing lever 93 inside the guiding tube 86. The top end of the screw rod 91 is higher than the guiding tube 86 and outside of the guiding tube 86. A knob 94 is mounted on the top end of the screw rod 91. Inside the guiding tube 86, the screw rod 91 is threaded into a sliding unit 95. The sliding unit 95 can be moved in a limiting range but can not rotate. There is a recovering spring 96 inside the lower portion of the guiding tube 86. The pushing lever 93 runs through the recovering spring 96. The top end of the recovering spring 96 contacts the pushing lever 93 and the bottom end thereof contacts the frame 81. The bottom end of the pushing lever 93 is outside of the guiding tube 86 and connected to a front end of a lever unit 97. The rear end of the lever unit 97 is pivotally connected to the frame 81. There is a resistance member 98 pivotally connected to the central portion of the lever unit 97. The resistance member 98 has an arc friction surface 99 for contacting the rotating member 84.
According to the components relationship of the adjustable resistance assembly 90, the pushing lever 93 bears upthrust force from the recovering spring 96 all the time. And the screw rod 91 also bears the upthrust force from the medium spring 92 all the time. Therefore, the sliding unit 95 is maintained at the top position in general. When the user rotates the knob 94, the screw rod 91 is rotated relative to the sliding unit 95 and moved linearly downward or upward. By a buffer effect of the medium spring 92, the pushing lever 93 is moved with the screw rod 91 in a slower rate. Thus, the front end of the lever unit 97 is gradually lifted or lowered and drives the resistance member 98 decreases or increases the friction resistance relative to the rotating member 84. If the user wants to quickly stop the rotating member 84 as exercising, he can directly press the knob 94 to make the screw rod 91 move downward with the sliding unit 95. And then the screw rod 91 and the medium spring 92 makes the pushing lever 93 press the front end of the lever unit 97 to make the friction surface 99 of the resistance member 98 contacts the rotating member 84 closely. Thus, he can stop the rotating member 84 at short time.
Another prior embodiment of the adjustable resistance assembly takes a torsion spring (not shown in FIG. 8) to replace the recovering spring 96 as mentioned above. The torsion spring is interconnected to the rear end of the lever unit 97 and the frame 81. A recovery elasticity of the torsion spring makes the front end of the lever unit 97 tends to rotate upward. Therefore, when the user rotates the knob 94 to move the pushing lever 93 upward or looses the pressing force, the lever unit 97 can push the pushing lever 93 upward and make the resistance member 98 leave the rotating member 84. The torsion spring works as the recovering spring 96.
This kind of adjustable resistance assembly is not only applied to stationary bicycles, but also applied to exercise apparatus which can be arranged a rotating member to produce exercise resistance such as cross trainer, stepper or skiing apparatus.
Although the functions of prior adjustable resistance assemblies are not inappropriate. However, the structure relationship and components of prior adjustable assemblies are still complicated and can be simplified to reduce manufacture cost.